Rego Grammar: Add v1 Tokens to the Accepted Token List

[SeanLedford]

What would you like to be added

Four keywords used in Rego v1 policies if, contains, every, in should be added to the parser's token table.

Why is this needed

The tokens above are parsed as variables via the grammar, which means many aspects of Rego syntax are currently being misinterpreted for parsing. There are several issues that this causes in modern Rego, which will have their own issues filed shortly

Implementation details

Very simple, the Rego.bnf grammar has a token table where we need to add these token types to:

tokens = [
        PACKAGE_TOKEN       = 'package'
        IMPORT_TOKEN        = 'import'
        AS                  = 'as'
        DEFAULT             = 'default'
        VAR_ASSIGN          = ':='
        UNIFICATION         = '='
        TRUE                = 'true'
        FALSE               = 'false'
        LPAREN              = '('
        RPAREN              = ')'
        LBRACK              = '['
        RBRACK              = ']'
        ELSE                = 'else'
        LBRACE              = '{'
        RBRACE              = '}'
        SEMICOLON           = ';'
        SOME                = 'some'
        COMMA               = ','
        DOT                 = '.'
        NOT                 = 'not'
        WITH                = 'with'
        COLLON              = ':'
        EQ                  = '=='
        NOT_EQ              = '!='
        LESS_OR_EQUAL       = '<='
        GREATER_OR_EQUAL    = '>='
        GREATHER            = '>'
        LESS                = '<'
        BIT_OR              = '|'
        BIT_AND             = '&'
        PLUS                = '+'
        MINUS               = '-'
        MUL                 = '*'
        QUOTIENT            = '/'
        REMAINDER           = '%'
        SET_OPEN            = 'set('
        NULL                = 'null'
        ASCII_LETTER        = 'regexp:[A-Za-z_][A-Za-z_0-9]*'
        NUMBER              = 'regexp:-?(0|[1-9]\d*)(\.\d+)?([eE][+-]?\d*)?'
        WHITE_SPACE         = 'regexp:\s+'
        STRING_TOKEN        = 'regexp:"([^\\"\r\n]|\\[^\r\n])*"?'
        RAW_STRING          = 'regexp:`[^`]*(`)?'
        COMMENT             = 'regexp:[ \t]*#[^\r\n]*'
    ]

^^^

Adding these four keywords here is the first step to updating our grammar.